Insulating ground pad



INVENTORS J. F. OESTERLING ET AL 2,751,

INSULATING GROUND PAD 2 Sheets-Sheet 1une26, 1956 Filed sept. 1o. 195s EEEEE mmm HQI-@gui51112451@j @@1355 M u ATTORNEY June 26, 1956 J. F. OESTERLING ETAL 2,751,609

INSULATING GROUND PAD Filed Sept. l0, 1953 2 Sheets-Sheet 2 INVENTORS James ed Oaserlizz Henry A. SZ'IQSKIL BY Q@ @Mm ATTORNEY Uid safes Petsnf 2,751,609 INSULA'HNG GROUND PAD James Fred Oesterling, Philadelphia, Henry A. `Snski,

Aldan, and Edward R. Frederick, Pittsburgh, Pa., assignor-s to the United States' of America as represented by the Secretary of the Army Application September 10, 1953, Serial No. 379,481

2 Claims. (Cl. 5--344) This invention relates to ground mats or pads and in general aims to provide'an insulating ground pad useful outdoors when the weather is well below F.

More specific objects are:

(l) To provide a pad which is flexible and usable at temperatures as low as 70 F.;

(2) To provide a pad which is comfortable and usable on rocky or uneven ground;

(3) To provide a pad so iiexible `that 'it may be rolled up and carried in a relatively small bundle or packet;

(4) To provide a pad which is much lighter in rweight than most inatable ground pads now in use;

(5) To provide a pad which needs no blowing up, hence is unlikely to accumulate frozen water from Water vapor blown into it;

(6) To provide a pad which may be made of nonstrategic materials of domestic origin;

(7) To provide a pad which may be manufactured on a quantity or line production basis;

(8) To provide a ground pad which is non-flammable and is incapable of absorbing water;

(9) To provide a ground pad made so that it may have a differential load-bearing capacity, with the highest capacity in areas which will be subjected to the most pressure from the body of the user;

(10) To provide a pad using spaced load-supporting blocks which may be so positioned that when the pad is rolled the blocks will fit into spaces between other blocks, thus minimizing the bulk or volume of the rolled pad.

in the accompanying drawings forming a part of this specification,

Fig. 1 is a top plan view of a ground mat or pad embodying the invention;

Fig. 2 is a side elevation of the same;

Fig. 3 is a perspective view of one of the resilient blocks used in making the mat;

Fig. 4 is a vertical section through a block like the one shown in Fig. 3 but illustrating a cloth backing fabric to which the block is attached by an adhesive;

Fig. 5 is a perspective View of a modified resilient block shown with integral attaching tins;

Fig. 6 is a vertical section through the block of Fig. 5 shown attached to a cloth backing fabric by stitching passing through the attaching fins;

Fig. 7 is a plan View of a ground mat without the resilient blocks, showing in dot and dash lines the different areas into which the mat is divided to sustain the different loads imposed by the human body; and

Figs. 8 and 9 are details in plan showing two alternative forms of blocks attached to cloth backing fabrics.

Referring first particularly to Figs. 1, 2, 3 and 4, the improved ground mat or pad consists in general of a exible fabric backing sheet 11 and a multiplicity of soft easily compressed blocks 12 secured as by an adhesive 13 to the sheet 11. The backing sheet could be of rubber, woven cloth (water-proofed if preferred), a non-woven plastic brous mat, or other flexible sheet material such as certain laminates. Extreme ilexibility is essential to erg" CC permit rolling or folding lthe backing sheetso that it may be packed for storage or transportation.4 The compressible lblocks 12 may be of a material such as Ensolite, a registered trademark of the U. S. Rubber Cornpany for a synthetic unicellular gas-expanded material which is a vulcanized blend of -plasticized polyvinyl chloride and butadiene-acrylonitrile copolymer. YHowever, we prefer to use a low temperature, low density unicellular, rubber-like polymer known as Special Arctic Polymer G, offered to the trade by The Sponge Rubber Products Co., Shelton, Connecticut, but originating from the General Tire and` Rubber Company. This polymer can be obtained in various degrees of softness; the"grade offered as 2e5 p. s. i. (compression test) is apparentlythe most desirable. This arcticpolymer withstands temperatures as low as F., that is, itis still flexible at Ythat temperature, and is so light in weight that a ground pad having 310 blocks each one inch square and about 1l/i6 in. thick weighed only 1.5 pounds. This weight contrasts rather sharply with the Atwo to seven pounds weight of inatable rubber pads heretofore used for vground pads by soldiers and Sportsmen. The adhesive may be Pliobond 20, a registered'trademark of The Goodyear Tire & Rubber Co. for its butadiene-acrylonitrile copolymer dissolved in methyl-ethyl-ketone to form an adhesive cement, or other resinous adhesive which can withstand low temperatures.

Instead of a rubber-like polymer cut in blocks as shown in Figs. 1 4, a dynel pile fabric, with a cotton or nylon backing and an elastomer coating may be cut into blocks and used. Such fabrics are employed as paddings in casualty bags. They have an average thickness of one-half inch to one inch when not compressed. The dynel pile fabrics are easily stitched to the fabric backing sheet 11 by commercial machines. They are very soft and wool-like and of low density and are more compressible and less resilient than Ensolite or the arctic polymer mentioned above.

In lieu of the adhesive 13, a modified form of the blocks 12a may have integral ns 15 (Fig. 5) and may be sewed by stitching 16 to the backing sheet 11, as shown in Fig. 6. If preferred, the blocks 12a may be joined together by the fins 15 and may be secured by the stitching 16 extending along both edges of long straight strips, each strip carrying a multiplicity of blocks 12a. As the blocks are easily compressed, stitching may be done by a commercial sewing machine and the stitching may pass through the entire thickness of the blocks.

In Fig. 1 the blocks are shown spaced equal distances apart throughout the area of the pad, and some blocks 12b are shown as incomplete; this will be the case if in manufacturing the pads the blocks 12 are evenly spaced over a backing sheet of large size and the sheet is then cut by a knife to the proper size and shape to make single pads. If the sheets 11 are initially cut to the proper size before assembling the blocks 12, there will be no incomplete or fragmentary blocks 12b.

It is obvious that with any ground pad supporting a human body, some areas are compressed far more than others. The areas subjected to the greatest compression are relatively small areas directly under the head, the shoulder blades, the buttocks and the heels of a person lying on the pad. Obviously these areas of greatest load bearing could be provided with blocks spaced relatively close together, and areas subjected to less load could have blocks spaced farther apart, while border areas could have fewer blocks spaced still farther apart. Fig. 7 shows in plan a backing sheet 11 having areas A which support the most load, other areas B which are subjected to less compression, and border areas C subjected to minimum loads. The blocks are not shown for simplicity of illustration but generally speaking, the spacing of the blocks for areasrA may be about that shown in Fig. l, the block spacing for areas B may be half again as far apart, and the spacing for areas C may be twice as far apart. Other spacings may of course be employed.y For a ground pad having an overall length of 79 in. and an overall width of 30 in., the A areas may total 5.1 sq. ft., B areas may total 3.9 sq. ft., and C areas may total 5.1 sq. ft.

All the blocks so far described are square. Instead of square blocks, cylindrical blocks 20 (Fig. 9) cut as sections of an extruded solid tube, or hexagonal blocks 21 (Fig. 8) cut out of Va solid sheet of the polymer may be used, or other shapes may be employed. The spacing of these shapes may be the same as described above in connection with the square blocks. Whatever their shape, it is very desirable to have the blocks spaced as far apart as possible without sacrificing the load-bearing capacity of the pad, because the blocks if too close together will interfere with rolling the pad into a small bundle.

The described pad has a far better insulating effect than the inflatable pads heretofore used, as actual eld tests in cold weather have proved. Also, our pad is more comfortable in cold weather than a blown-up rubber ground pad. Our pad may be used advantageously with sleeping bags such as are issued to members of the U. S. Army ground forces; or if preferred, our pad could be physically incorporated in the Walls of a sleeping bag.

What we claim is:

1. An insulating ground pad consisting of a ilexible fabric ibacking, and a multiplicity of compressible solid elastomer blocks each securely iixed to one face of the fabric backing, the blocks being each capable of supporting a compression load of about 2 p. s. i. and being spaced suthciently far apart from each other to permit the pad to be rolled up without excessive bulk arising from contact of blocks with other blocks; the elastomer being capable of maintaining its compressibility at temperatures as low as -70 F., and being a good heat insulator and a non-absorbent of moisture.

2. An insulating ground pad consisting of a ilexible substantially imperforate cloth backing, and a multiplicity of spaced solid blocks of soft rubber or rubber-like material each securely fixed to one face of the cloth backing, the blocks all being of the same dimensions but being arranged relatively close together in those areas which will bear the heaviest loads when a human body lies on the pad and being much farther apart in those areas which will support minimum loads from a prone human body, the material of the .blocks being capable of resisting temperatures as low as 70 F. without loss of compressibility.

References Cited in the file of this patent UNITED STATES PATENTS Robell a Apr. 18, 

1. AN INSULATING GROUND PAD CONSISTING OF A FLEXIBLE FABRIC BACKING, AND A MULTIPLICITY OF COMPRESSIBLE SOLID ELASTOMER BLOCKS EACH SECURELY FIXED TO ONE FACE OF THE FABRIC BACKING, THE BLOCKS BEING EACH CAPABLE OF SUPPORTING A COMPRESSION LOAD OF ABOUT 2 P.S.I. AND BEING SPACED SUFFICIENTLY FAR APART FROM EACH OTHER TO PERMIT THE PAD TO BE ROLLED UP WITHOUT EXCESSIVE BULK ARISING FROM CONTACT OF BLOCKS WITH OTHER BLOCKS; THE ELASTOMER BEING CAPABLE OF MAINTAINING ITS COMPRESSIBILITY AT TEMPERATURES AS LOW AS -70* F., AND BEING A GOOD HEAT INSULATOR AND A NON-ABSORBENT OF MOISTURE. 